CN117346930A - Optical fiber touch sensor and preparation method thereof - Google Patents

Optical fiber touch sensor and preparation method thereof Download PDF

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Publication number
CN117346930A
CN117346930A CN202311286106.8A CN202311286106A CN117346930A CN 117346930 A CN117346930 A CN 117346930A CN 202311286106 A CN202311286106 A CN 202311286106A CN 117346930 A CN117346930 A CN 117346930A
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optical fiber
layer
cover layer
guide cover
light guide
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岳士超
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Southeast University
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Southeast University
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L1/00—Measuring force or stress, in general
    • G01L1/24—Measuring force or stress, in general by measuring variations of optical properties of material when it is stressed, e.g. by photoelastic stress analysis using infrared, visible light, ultraviolet
    • G01L1/242—Measuring force or stress, in general by measuring variations of optical properties of material when it is stressed, e.g. by photoelastic stress analysis using infrared, visible light, ultraviolet the material being an optical fibre
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G01B11/16—Measuring arrangements characterised by the use of optical techniques for measuring the deformation in a solid, e.g. optical strain gauge
    • G01B11/18—Measuring arrangements characterised by the use of optical techniques for measuring the deformation in a solid, e.g. optical strain gauge using photoelastic elements
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06N—COMPUTING ARRANGEMENTS BASED ON SPECIFIC COMPUTATIONAL MODELS
    • G06N3/00—Computing arrangements based on biological models
    • G06N3/02—Neural networks
    • G06N3/04—Architecture, e.g. interconnection topology
    • G06N3/0464—Convolutional networks [CNN, ConvNet]
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06N—COMPUTING ARRANGEMENTS BASED ON SPECIFIC COMPUTATIONAL MODELS
    • G06N3/00—Computing arrangements based on biological models
    • G06N3/02—Neural networks
    • G06N3/08—Learning methods
    • G06N3/09—Supervised learning
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06V—IMAGE OR VIDEO RECOGNITION OR UNDERSTANDING
    • G06V10/00—Arrangements for image or video recognition or understanding
    • G06V10/70—Arrangements for image or video recognition or understanding using pattern recognition or machine learning
    • G06V10/764—Arrangements for image or video recognition or understanding using pattern recognition or machine learning using classification, e.g. of video objects
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06V—IMAGE OR VIDEO RECOGNITION OR UNDERSTANDING
    • G06V10/00—Arrangements for image or video recognition or understanding
    • G06V10/70—Arrangements for image or video recognition or understanding using pattern recognition or machine learning
    • G06V10/82—Arrangements for image or video recognition or understanding using pattern recognition or machine learning using neural networks

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Theoretical Computer Science (AREA)
  • General Physics & Mathematics (AREA)
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  • Health & Medical Sciences (AREA)
  • Artificial Intelligence (AREA)
  • Computing Systems (AREA)
  • Software Systems (AREA)
  • General Health & Medical Sciences (AREA)
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  • Computer Vision & Pattern Recognition (AREA)
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  • Computational Linguistics (AREA)
  • Data Mining & Analysis (AREA)
  • Molecular Biology (AREA)
  • General Engineering & Computer Science (AREA)
  • Mathematical Physics (AREA)
  • Force Measurement Appropriate To Specific Purposes (AREA)

Abstract

The invention discloses an optical fiber touch sensor and a preparation method thereof, wherein the optical fiber touch sensor comprises one or more touch units, the touch units are connected with a camera through optical fibers, the camera is connected with a data processing unit, and the data processing unit is used for processing and calculating image data to obtain touch information; the touch unit comprises a shell, a light collecting layer is arranged in the shell, a light guide cover layer is attached to the upper part of the light collecting layer, and a frame is used for fixing the light guide cover layer; the frame is arranged at the upper part of the shell; the multi-color light source is arranged on one side of the light guide cover layer, and the lower surface of the light guide cover layer is of a convex array structure; the optical fiber passes through the shell and is connected with the light collecting layer. The optical fiber touch sensor has low manufacturing cost and strong anti-interference capability.

Description

Optical fiber touch sensor and preparation method thereof
Technical Field
The invention relates to an optical fiber touch sensor, and belongs to the technical field of intelligent sensing.
Background
Optical fiber tactile sensors are a sensor technology for measuring touch and strain, which uses the properties of optical fibers to detect changes in the external environment. The basic principle of an optical fiber touch sensor is to use an external strain on an optical signal propagating in an optical fiber, which strain causes a change in the optical signal in the optical fiber, such as a phase change or a light intensity change, which can be measured and analyzed to determine external touch or strain information. The optical fiber touch sensor can adopt different working principles, including an interference type, a scattering type and a light intensity type. The interferometric fiber optic sensor is based on the change in optical path difference caused by external strain, the scattering sensor is based on the change in scattered light signal, and the light intensity sensor focuses on the change in light intensity. In the existing optical fiber touch sensor, the adopted grating optical fiber has strict requirements on optical signal demodulation equipment, high cost and complex manufacturing process of the grating optical fiber. At present, aiming at the optical fiber touch sensor technology, at least the following problems are found:
1) The grating in the grating fiber belongs to a high-precision structure, the preparation process is complex, and the equipment is expensive;
2) The grating signal demodulator of the grating fiber belongs to high-precision electronic equipment and has high price;
3) The light intensity type touch sensor is suitable for single-point touch measurement, and the touch array is difficult to realize.
CN115574998A discloses an optical fiber facula tactile sensor with a reflective probe structure, wherein the force applied on a probe contact member causes deformation of a reflector, so that the change of an output facula is caused, and a facula pattern is used as a sensing signal, and the change of the bending state of the output optical fiber has small influence on the output facula due to the fact that the facula change is mainly caused by the deformation of the reflector, so that the optical fiber has bending interference resistance; however, this approach is difficult to perform large-area and large-scale tactile measurements for single-point tactile detection. CN116067542a discloses a method for identifying the magnitude and direction of three-dimensional force by a mechanical anisotropic cylinder fiber bragg grating type three-dimensional force touch sensor, wherein a cylinder is compressed along a Z axis under the action of normal force, so that two FBGs are compressed simultaneously, and the central wavelength drifts towards the short wavelength direction simultaneously; the angle of the tangential force is identified through the positive and negative and proportional relations of the center wavelength drift amounts of the two FBGs, and the magnitude of the tangential force is identified through the amplitude value of the drift amounts; however, the scheme adopts the grating fiber as a sensitive unit, the grating preparation process is complex, and the grating signal demodulation cost is high.
Disclosure of Invention
The technical problems to be solved by the invention are as follows: the existing optical fiber touch sensor has the defects that the optical fiber touch array sensor has higher production cost due to the high equipment cost of a grating signal demodulator because of complex grating and preparation process;
the invention further aims to solve the technical problems that: the existing optical fiber touch sensor is difficult to realize large-area touch measurement.
In order to solve the technical problems, the invention provides an optical fiber touch sensor, which comprises one or more touch units, wherein the touch units are connected with a camera 6 through an optical fiber 5, the camera 6 is connected with a data processing unit 7, and the data processing unit 7 is used for processing and calculating image data to obtain touch information;
the touch unit comprises a shell 8, a light collecting layer 4 is arranged in the shell 8, a light guide cover layer 1 is attached to the upper part of the light collecting layer 4, and a frame 3 fixes the light guide cover layer; the frame 3 is arranged at the upper part of the shell 8;
the multi-color light source 2 is arranged on one side of the light guide cover layer 1, and the lower surface of the light guide cover layer 1 is of a convex array structure;
the optical fiber 5 is connected to the light collecting layer 4 through the housing 8.
In the optical fiber touch sensor, the multi-color light source 2 is fixed in the light source preformed hole of the frame 3; the multicolor light sources 2 are uniformly arranged, and the distance between the multicolor light sources is 5 mm.
In the foregoing optical fiber touch sensor, the protrusion on the lower surface of the light guiding cover layer 1 is a hemisphere, a pyramid, a cone or a table.
In the optical fiber touch sensor, when the protrusions are hemispherical, the diameter of the hemispherical is 1.8 mm, the distance between the hemispherical is 2 mm, and the array scale is 10 in each row, and the total number of the array scales is 10.
In the optical fiber touch sensor, the light guide cover layer 1 is made of dimethylsiloxane (PDMS) material, and the thickness is 2-3 mm; the light collecting layer 4 is made of polydimethylsiloxane PDMS; the shell 8 is made of polylactic acid PLA.
In the optical fiber touch sensor, the number of the touch units is 4, and the touch units are arranged in a 2 x 2 array; or (b)
The number of the haptic units is 7, each haptic unit is hexagonal, and the haptic unit at one center position externally surrounds 6 haptic units.
In the foregoing optical fiber touch sensor, in the data processing unit 7, an image data processing module is operated, and is used for processing and calculating image data, where the image data processing module processes the image data by adopting a convolutional neural network, and the convolutional neural network structure is as follows:
c1: an input layer (101) for receiving an input of RGB images of the size 224 x 3 for receiving image data to be classified;
c2, a first convolution layer (102) for performing convolution calculation on the C1 output image and converting the image matrix dimension into 224×224×32;
a maximum pooling layer (103) for reducing the data dimension of the C2 output image to 112×112×32;
a second convolution layer (104) for convolving the output of the previous layer to increase the image matrix dimension to 112 x 64;
a second max pooling layer (105) to reduce the data dimension to 56 x 64;
a third convolution layer (106) that increases the image data matrix dimension to 56 x 128;
a third max pooling layer (107) reducing the previous layer data dimension to 28 x 128;
a data flattening layer (108) for flattening the previous layer 28 x 128 matrix of image data into a 2048 element vector;
c9, a fully connected layer (109) with a ReLU activation function, for processing flattened data of a previous layer;
c10: a final fully connected layer (110) having a softmax activation function for classifying different categories of data of a previous layer; the softmax activation function outputs a probability distribution of the predicted category for indicating the location of the force and the magnitude of the force, the output tag with the highest probability reflecting that the image is from a particular test location and magnitude of the force.
A preparation method of an optical fiber touch sensor comprises the following steps:
s1: designing a die of a top light guide cover layer of the optical fiber touch sensor; the die comprises an upper part and a lower part, and the lower part die comprises a concave part matched with the convex array structure;
s2: the method comprises the steps of manufacturing an upper mold and a lower mold of a top light guide cover layer of an optical fiber touch sensor by adopting polylactic acid PLA material and using an extrusion type 3D printer;
s3: assembling the upper and lower mold sections together and temporarily sealing with a silicone adhesive to prevent leakage of polydimethylsiloxane PDMS;
s4: mixing the PDMS-sleeved silica gel with a cross-linking agent according to the ratio of 10:1, pouring the mixture into a covering layer mold, and then curing for 0.8-1 hour in a hot box at 70-80 ℃;
s5, demolding PDMS from a PLA mold to form a light guide cover layer, then cutting the light guide cover layer into a set shape and size, wherein the cut light guide cover layer comprises a margin edge with an additional set size and is used for being adhered to a frame 3 supporting the light guide cover layer;
s6, designing and manufacturing a shell 8 of the touch sensor, and then inserting a section of optical fiber 5 into the bottom of the shell 8;
s7, injecting polydimethylsiloxane PDMS into the shell 8, and curing for 0.8-1 hour in an oven at 70-80 ℃ to prepare the light collecting layer 4;
s8, designing and using PLA material to manufacture a frame 3 for fixing the light guide cover layer 1, wherein a light source bracket is arranged on the frame 3 for placing the multi-color light source 2;
s9, assembling the light guide cover layer 1, the shell 8 and the frame 3 together to enable the light guide cover layer, the light collecting layer and the optical fibers to be assembled together to jointly form a touch unit of the optical fiber touch sensor;
s10, connecting an optical fiber of the touch unit to the camera 6;
s11: the camera 6 is connected with a data image processing system 7 to form an optical fiber touch sensor.
In the aforementioned method for manufacturing an optical fiber touch sensor, in step S8, mounting holes of LED light sources are reserved on the light source bracket, and the number of the mounting holes is the same as the number of basic colors of the multicolor light sources.
The preparation method of the optical fiber touch sensor further comprises the following steps between the steps S9 and S10:
preparing four haptic elements according to steps S1-S9 and assembling according to a 2 x 2 array arrangement; or (b)
7 haptic elements were prepared as in steps S1-S9, with a centrally located haptic element surrounding 6 haptic elements externally.
The invention has the beneficial effects that: the optical fiber touch sensor provided by the invention has the advantages that the sensing structure simulates a complex structure between the skin epidermis and the dermis, the sensing principle utilizes the image information formed at the far end of the optical fiber after the multi-color light field enters the multi-mode optical fiber to propagate dispersion, and the image information is analyzed and calculated to obtain the touch information. The sensor comprises a light guide cover layer, a multi-color light source, a light collecting layer, a shell, a multimode fiber, a camera and a data processing system; the multicolor light source emits light into the light guide cover layer, a structural light field is formed in the light guide cover layer, a bionic bulge is formed on the lower surface of the light guide cover layer and is contacted with the light collecting layer, when a touch force or temperature change is applied to the upper surface of the light guide cover layer, the contact between the lower surface of the light guide cover layer and the upper surface of the light collecting layer can change, the structural light is caused to change, the changed light field can be collected by the light collecting layer, enters the near end of an optical fiber, is transmitted to the far end of the optical fiber after dispersion by the optical fiber, a camera collects a far-end color image of the optical fiber, and image data is analyzed and processed by a data processing system to obtain touch information on the cover layer.
The optical fiber touch sensor provided by the invention has the advantages that the structure of the bulge-shaped array is designed as a cover layer sensing structure, the multicolor light field is adopted as a carrier of touch information, the machine learning method is utilized to process the image data of the far end of the optical fiber, and compared with other piezoresistive, capacitive, grating optical fiber and other touch sensors, the optical fiber touch sensor has low preparation cost, and the defects of complex grating signal demodulation system and high price of the traditional grating optical fiber touch sensor are overcome.
The optical fiber touch sensor can form a touch sensing array by a plurality of touch units, and overcomes the defects of more leads, easy failure and high cost of the traditional piezoresistive and capacitive sensor.
Meanwhile, the combination arrangement of the touch units can realize large-area touch measurement, reduce the difficulty in realizing large-area touch measurement, and have reference value for other occasions such as deformation detection.
Drawings
FIG. 1 is a schematic diagram of a fiber optic tactile sensor assembly according to embodiment 1 of the present invention;
FIG. 2 is a schematic diagram of a convolutional neural network of an image processing system of an optical fiber touch sensor according to embodiment 1 of the present invention;
FIG. 3 is a schematic view of the light field of the internal structure of the light guiding cover layer using 3-color LEDs as the multi-color light source in embodiment 1 of the invention;
fig. 4 is a schematic diagram of a 2 x 2 haptic array formed by using 4 haptic elements according to embodiment 2 of the present invention;
FIG. 5 is a schematic diagram of a large area haptic array using 7 hexagonal haptic cells in example 3 of the present invention.
Reference numerals: 1. the light guide cover layer, the multi-color light source, the frame, the light collecting layer, the optical fiber, the camera 7, the data processing unit and the shell.
Detailed Description
The following describes specific embodiments of the present invention with reference to the drawings.
Example 1
The embodiment provides an optical fiber touch sensor, which comprises a touch unit, wherein the touch unit is connected with a camera 6 through an optical fiber 5, the camera 6 is connected with a data processing unit 7, and the data processing unit 7 is used for processing and calculating image data to obtain touch information;
the touch unit comprises a shell 8, a light collecting layer 4 is arranged in the shell 8, a light guide cover layer 1 is attached to the upper part of the light collecting layer 4, and a frame 3 fixes the light guide cover layer; the frame 3 is arranged at the upper part of the shell 8;
the multi-color light source 2 is arranged on one side of the light guide cover layer 1; the multicolor light source 2 is fixed in a light source preformed hole of the frame 3; the multicolor light sources 2 are uniformly arranged, and the distance between the multicolor light sources is 5 mm;
the lower surface of the light guide cover layer 1 is of a convex array structure;
the bulges on the lower surface of the light guide cover layer 1 can be hemispherical, pyramid, cone or table body; when the protrusions are hemispherical, the diameter of the hemispherical is 1.8 mm, the distance between the hemispherical is 2 mm, for example, the array scale is 10 in each row, and the total number of the array is 10, namely 100;
the light guide cover layer 1 and the light collecting layer are stacked together, and the light guide cover layer 1 is fixed with the frame 3 through PDMS;
the light guide cover layer 1 is made of dimethylsiloxane PDMS material, and the thickness is about 2-3 mm;
the light collecting layer 4 is made of polydimethylsiloxane PDMS;
the shell 8 is made of polylactic acid PLA.
The optical fiber 5 is connected to the light collecting layer 4 through the housing 8.
The optical fiber touch sensor of the invention has the working principle that: the lower surface of the light guide cover layer 1 is of a bulge-shaped array structure, the bulge-shaped array of the light guide cover layer is used for realizing light modulation so as to sense external touch information, the external touch information comprises force, temperature and the like, the bulge-shaped array structure is attached to the light collecting layer, light emitted by the multicolor light source 2 forms structural light in the light guide cover layer 1, the structural light is collected by the light collecting layer 4 and enters the optical fiber 5 for propagation dispersion, the far end of the optical fiber 5 is connected with the camera 6 to collect color images of the far end of the optical fiber 5, the image data are sent to the data processing system 7, and the touch information is calculated after the image data are processed.
In the data processing unit 7, an image data processing module is operated, and is used for processing and calculating image data, the image data processing module processes the image data by adopting a convolutional neural network, as shown in fig. 2, and the convolutional neural network has the structure that:
c1: an input layer (101) for receiving an input of RGB images of the size 224 x 3 for receiving image data to be classified;
c2, a first convolution layer (102) for performing convolution calculation on the C1 output image and converting the image matrix dimension into 224×224×32;
a maximum pooling layer (103) for reducing the data dimension of the C2 output image to 112×112×32;
a second convolution layer (104) for convolving the output of the previous layer to increase the image matrix dimension to 112 x 64;
a second max pooling layer (105) to reduce the data dimension to 56 x 64;
a third convolution layer (106) that increases the image data matrix dimension to 56 x 128;
a third max pooling layer (107) reducing the previous layer data dimension to 28 x 128;
a data flattening layer (108) for flattening the previous layer 28 x 128 matrix of image data into a 2048 element vector;
c9, a fully connected layer (109) with a ReLU activation function, for processing flattened data of a previous layer;
c10: a final fully connected layer (110) having a softmax activation function for classifying different categories of data of a previous layer; the softmax activation function outputs a probability distribution of the predicted category for indicating the location of the force and the magnitude of the force, the output tag with the highest probability reflecting that the image is from a particular test location and magnitude of the force.
The invention relates to a preparation method of an optical fiber touch sensor, which comprises the following steps:
s1: designing a die of a top light guide cover layer of the optical fiber touch sensor; the mold comprises an upper part and a lower part, the lower part mold comprises a concave part matched with the convex array structure, a cavity between the upper mold and the lower mold is a cavity for manufacturing the light guide cover layer 1, and the volume of the cavity is 24 mm by 3.5 mm;
s2: the method comprises the steps of manufacturing an upper mold and a lower mold of a top light guide cover layer of an optical fiber touch sensor by adopting polylactic acid PLA material and using an extrusion type 3D printer;
s3: assembling the upper and lower mold sections together and temporarily sealing with a silicone adhesive to prevent leakage of polydimethylsiloxane PDMS; the silica gel is conventional AB type silica gel, and is cured for 2 hours at 60 ℃ in a hot air box;
s4: mixing the silicone rubber sleeved with the polydimethylsiloxane and the cross-linking agent according to the proportion of 10:1, pouring the mixture into a covering layer mold, and then curing for 0.8-1 hour in a hot box at 70-80 ℃;
s5, demolding Polydimethylsiloxane (PDMS) from a PLA mold to form a light guide cover layer, then cutting the light guide cover layer into a set shape and size, such as a square with side length of 22 mm multiplied by 22 mm, wherein the cut light guide cover layer comprises a margin edge with an additional set size for adhering to a frame 3 supporting the light guide cover layer;
the working area of the light guide cover layer is 20 mm by 20 mm, the rest edge is 2 mm wide, and PDMS is used for bonding with the frame 3;
s6, designing and manufacturing a shell 8 of the touch sensor, and then inserting a section of optical fiber 5 into the bottom of the shell 8, wherein the length of the optical fiber depends on the actual distance between the camera and the touch sensor;
printing the shell 8 with PLA material, the shell 8 size being 22 mm x 22 mm, the cavity height being 15 mm; the length of the optical fiber depends on the distance between the camera and the mounting position of the sensor in the specific embodiment;
s7, injecting polydimethylsiloxane PDMS into the shell 8, and curing for 0.8-1 hour in an oven at 70-80 ℃ to prepare the light collecting layer 4;
s8, designing and using PLA material to manufacture a frame 3 for fixing the light guide cover layer, wherein a light source bracket is arranged on the frame 3 for placing the multi-color light source 2;
in step S8, a mounting hole of the LED light source is reserved on the light source bracket; the number of the mounting holes is the same as the basic color number of the multicolor light source, as shown in fig. 3, and the number of the mounting holes is 3 when the LED light source has 3 colors;
s9, assembling the light guide cover layer 1, the shell 8 and the frame 3 together to enable the light guide cover layer, the light collecting layer and the optical fibers to be assembled together to jointly form a touch unit of the optical fiber touch sensor;
s10, connecting the optical fiber of the touch unit in the step S9 to the camera 6;
s11: the camera 6 is connected with a data image processing system 7 to form an optical fiber touch sensor.
Example 2
As shown in fig. 4, the present embodiment provides an optical fiber touch sensor, which includes a plurality of touch units, each touch unit is connected with a camera 6 through an optical fiber 5, the camera 6 is connected with a data processing unit 7, and the data processing unit 7 is used for processing and calculating image data to obtain touch information;
the touch unit comprises a shell 8, a light collecting layer 4 is arranged in the shell 8, a light guide cover layer 1 is attached to the upper part of the light collecting layer 4, and a frame 3 fixes the light guide cover layer; the frame 3 is arranged at the upper part of the shell 8;
the multi-color light source 2 is arranged on one side of the light guide cover layer 1;
the lower surface of the light guide cover layer 1 is of a convex array structure;
the optical fiber 5 is connected to the light collecting layer 4 through the housing 8.
The number of the tactile units is 4, and the tactile units are arranged in a 2 x 2 array; the optical fiber 5 of each haptic unit is connected to a camera 6, and the camera 6 is connected to an image data processing system 7.
The preparation method of the optical fiber touch sensor of the embodiment comprises the following steps:
s1: designing a die of a top light guide cover layer of the optical fiber touch sensor; the mold comprises an upper part and a lower part, the lower part mold comprises a concave part matched with the convex array structure, a cavity between the upper mold and the lower mold is a cavity for manufacturing the light guide cover layer 1, and the volume of the cavity is 24 mm by 3.5 mm;
s2: the method comprises the steps of manufacturing an upper mold and a lower mold of a top light guide cover layer of an optical fiber touch sensor by adopting polylactic acid PLA material and using an extrusion type 3D printer;
s3: assembling the upper and lower mold sections together and temporarily sealing with a silicone adhesive to prevent leakage of polydimethylsiloxane PDMS;
s4: mixing the silicone rubber sleeved with the polydimethylsiloxane and the cross-linking agent according to the proportion of 10:1, pouring the mixture into a covering layer mold, and then curing for 0.8-1 hour in a hot box at 70-80 ℃;
s5, demolding Polydimethylsiloxane (PDMS) from a PLA mold to form a light guide cover layer, then cutting the light guide cover layer into a set shape and size, such as a square with side length of 22 mm multiplied by 22 mm, wherein the cut light guide cover layer comprises a margin edge with an additional set size for adhering to a frame 3 supporting the light guide cover layer;
s6, designing and using PLA material to manufacture the shell 8 of the touch sensor, and then inserting a section of optical fiber 5 into the bottom of the shell 8, wherein the length of the optical fiber depends on the actual distance between the camera and the touch sensor;
s7, injecting polydimethylsiloxane PDMS into the shell 8, and curing for 0.8-1 hour in an oven at 70-80 ℃ to prepare the light collecting layer 4;
s8, designing and using PLA material to manufacture a frame 3 for fixing the light guide cover layer, wherein a light source bracket is arranged on the frame 3 for placing the multi-color light source 2;
s9, assembling the light guide cover layer 1, the shell 8 and the frame 3 together to enable the light guide cover layer, the light collecting layer and the optical fibers to be assembled together to jointly form a touch unit of the optical fiber touch sensor;
s10, preparing four tactile units according to the steps S1-S9, and arranging and assembling according to a 2 x 2 array;
s11, connecting four optical fibers of the four tactile units in S10 to the camera 6;
s12: the camera 6 is connected with a data image processing system 7 to form an optical fiber touch sensor of a 2 x 2 touch sensing array.
Example 3
As shown in fig. 5, the present embodiment provides an optical fiber touch sensor, which includes a plurality of touch units, each touch unit is connected with a camera 6 through an optical fiber 5, the camera 6 is connected with a data processing unit 7, and the data processing unit 7 is used for processing and calculating image data to obtain touch information;
the touch unit comprises a shell 8, a light collecting layer 4 is arranged in the shell 8, a light guide cover layer 1 is attached to the upper part of the light collecting layer 4, and a frame 3 fixes the light guide cover layer; the frame 3 is arranged at the upper part of the shell 8;
the multi-color light source 2 is arranged on one side of the light guide cover layer 1;
the lower surface of the light guide cover layer 1 is of a convex array structure;
the optical fiber 5 is connected to the light collecting layer 4 through the housing 8.
The number of the tactile units is 7, each tactile unit is hexagonal, and 6 tactile units are surrounded outside one tactile unit at the central position; the optical fiber 5 of each haptic unit is connected to a camera 6, and the camera 6 is connected to an image data processing system 7.
The preparation method of the optical fiber touch sensor of the embodiment comprises the following steps:
s1: designing a die of a top light guide cover layer of the optical fiber touch sensor; the mold comprises an upper part and a lower part, the lower part mold comprises a concave part matched with the convex array structure, a cavity between the upper mold and the lower mold is a cavity for manufacturing the light guide cover layer 1, and the volume of the cavity is 24 mm by 3.5 mm;
s2: the method comprises the steps of manufacturing an upper mold and a lower mold of a top light guide cover layer of an optical fiber touch sensor by adopting polylactic acid PLA material and using an extrusion type 3D printer;
s3: assembling the upper and lower mold sections together and temporarily sealing with a silicone adhesive to prevent leakage of polydimethylsiloxane PDMS;
s4: mixing the silicone rubber sleeved with the polydimethylsiloxane and the cross-linking agent according to the proportion of 10:1, pouring the mixture into a covering layer mold, and then curing for 0.8-1 hour in a hot box at 70-80 ℃;
s5, demolding Polydimethylsiloxane (PDMS) from a PLA mold to form a light guide cover layer, then cutting the light guide cover layer into a set shape and size, such as a square with side length of 22 mm multiplied by 22 mm, wherein the cut light guide cover layer comprises a margin edge with an additional set size for adhering to a frame 3 supporting the light guide cover layer;
s6, designing and using PLA material to manufacture the shell 8 of the touch sensor, and then inserting a section of optical fiber 5 into the bottom of the shell 8, wherein the length of the optical fiber depends on the actual distance between the camera and the touch sensor;
s7, injecting polydimethylsiloxane PDMS into the shell 8, and curing for 0.8-1 hour in an oven at 70-80 ℃ to prepare the light collecting layer 4;
s8, designing and using PLA material to manufacture a frame 3 for fixing the light guide cover layer, wherein a light source bracket is arranged on the frame 3 for placing the multi-color light source 2;
s9, assembling the light guide cover layer 1, the shell 8 and the frame 3 together to enable the light guide cover layer, the light collecting layer and the optical fibers to be assembled together to jointly form a touch unit of the optical fiber touch sensor;
s10, preparing 7 tactile units according to the steps S1-S9, wherein the outside of the tactile unit at the central position surrounds 6 tactile units;
s11, 7 optical fibers of the 7 tactile units in S10 are connected to the camera 6;
s12: the camera 6 is connected with a data image processing system 7 to form an optical fiber touch sensor.
While the embodiments of the present invention have been described in detail and with reference to the drawings, the foregoing description is only a preferred embodiment of the present invention, and it should be noted that modifications and variations can be made by those skilled in the art without departing from the technical principles of the present invention, and such modifications and variations should also be regarded as being within the scope of the invention.

Claims (10)

1. The optical fiber touch sensor comprises one or more touch units, and is characterized in that the touch units are connected with a camera (6) through optical fibers (5), the camera (6) is connected with a data processing unit (7), and the data processing unit (7) is used for processing and calculating image data to obtain touch information;
the touch unit comprises a shell (8), a light collecting layer (4) is arranged in the shell (8), a light guide cover layer (1) is attached to the upper part of the light collecting layer (4), and the light guide cover layer is fixed by a frame (3); the frame (3) is arranged at the upper part of the shell (8);
the multi-color light source (2) is arranged on one side of the light guide cover layer (1), and the lower surface of the light guide cover layer (1) is of a convex array structure;
the optical fiber (5) passes through the shell (8) and is connected with the light collecting layer (4).
2. The optical fiber touch sensor according to claim 1, wherein the multicolor light source (2) is fixed in a light source preformed hole of the frame (3); the multicolor light sources (2) are uniformly arranged, and the distance between the multicolor light sources is 5 mm.
3. A fibre optic tactile sensor according to claim 1, wherein the protrusions of the lower surface of the light guiding cover layer (1) are hemispherical, pyramidal, conical or mesa-shaped.
4. A fibre optic tactile sensor according to claim 3, wherein when the protrusions are hemispherical, the hemispherical diameter is 1.8 mm, the spacing between the hemispheres is 2 mm, the array scale is 10 per row for a total of 10 rows.
5. The optical fiber touch sensor according to claim 1, wherein the light guiding cover layer (1) is made of PDMS material and has a thickness of 2-3 mm; the light collecting layer (4) is made of PDMS; the shell (8) is made of PLA.
6. The optical fiber touch sensor according to claim 1, wherein 4 touch units are arranged in a 2 x 2 array; or (b)
The number of the haptic units is 7, each haptic unit is hexagonal, and the haptic unit at one center position externally surrounds 6 haptic units.
7. The optical fiber touch sensor according to claim 1, wherein in the data processing unit (7), an image data processing module is operated for processing and calculating image data, the image data processing module processes the image data by adopting a convolutional neural network, and the convolutional neural network structure is as follows:
c1: an input layer (101) for receiving an input of RGB images of the size 224 x 3 for receiving image data to be classified;
c2, a first convolution layer (102) for performing convolution calculation on the C1 output image and converting the image matrix dimension into 224×224×32;
a maximum pooling layer (103) for reducing the data dimension of the C2 output image to 112×112×32;
a second convolution layer (104) for convolving the output of the previous layer to increase the image matrix dimension to 112 x 64;
a second max pooling layer (105) to reduce the data dimension to 56 x 64;
a third convolution layer (106) that increases the image data matrix dimension to 56 x 128;
a third max pooling layer (107) reducing the previous layer data dimension to 28 x 128;
a data flattening layer (108) for flattening the previous layer 28 x 128 matrix of image data into a 2048 element vector;
c9, a fully connected layer (109) with a ReLU activation function, for processing flattened data of a previous layer;
c10: a final fully connected layer (110) having a softmax activation function for classifying different categories of data of a previous layer; the softmax activation function outputs a probability distribution of the predicted category for indicating the location of the force and the magnitude of the force, the output tag with the highest probability reflecting that the image is from a particular test location and magnitude of the force.
8. The preparation method of the optical fiber touch sensor is characterized by comprising the following steps of:
s1: designing a die of a top light guide cover layer of the optical fiber touch sensor; the die comprises an upper part and a lower part, and the lower part die comprises a concave part matched with the convex array structure;
s2: adopting PLA material, and manufacturing an upper part mold and a lower part mold of a top light guide cover layer of the optical fiber touch sensor by using an extrusion type 3D printer;
s3: assembling the upper and lower mold parts together and temporarily sealing with a silicone adhesive to prevent PDMS leakage;
s4: mixing the PDMS-sleeved silica gel with a cross-linking agent according to the ratio of 10:1, pouring the mixture into a covering layer mold, and then curing for 0.8-1 hour in a hot box at 70-80 ℃;
s5, demolding PDMS from a PLA mold to form a light guide cover layer, then cutting the light guide cover layer into a set shape and size, wherein the cut light guide cover layer comprises a margin edge with an additional set size and is used for being adhered to a frame (3) supporting the light guide cover layer;
s6, designing and manufacturing a shell (8) of the touch sensor, and then inserting a section of optical fiber (5) at the bottom of the shell (8);
s7, injecting PDMS into the shell (8), and curing in an oven at 70-80 ℃ for 0.8-1 hour to prepare a light collecting layer (4);
s8, designing and using PLA materials to manufacture a frame (3) for fixing the light guide cover layer (1), wherein a light source bracket is arranged on the frame (3) for placing the multi-color light source (2);
s9, assembling the light guide cover layer (1), the shell (8) and the frame (3) together to enable the light guide cover layer, the light collecting layer and the optical fibers to be assembled together to jointly form a touch unit of the optical fiber touch sensor;
s10, connecting an optical fiber of the touch unit to a camera (6);
s11: the camera (6) is connected with a data image processing system (7) to form the optical fiber touch sensor.
9. The method for manufacturing an optical fiber touch sensor according to claim 8, wherein in step S8, mounting holes of the LED light sources are reserved on the light source bracket, and the number of the mounting holes is the same as the number of basic colors of the multicolor light sources.
10. The method of manufacturing an optical fiber touch sensor according to claim 8, further comprising the steps of, between steps S9 and S10:
preparing four haptic elements according to steps S1-S9 and assembling according to a 2 x 2 array arrangement; or (b)
7 haptic elements were prepared as in steps S1-S9, with a centrally located haptic element surrounding 6 haptic elements externally.
CN202311286106.8A 2023-10-07 2023-10-07 Optical fiber touch sensor and preparation method thereof Pending CN117346930A (en)

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CN202311286106.8A CN117346930A (en) 2023-10-07 2023-10-07 Optical fiber touch sensor and preparation method thereof

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
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Publication Number Publication Date
CN117346930A true CN117346930A (en) 2024-01-05

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